#include <bits/stdc++.h> //Andrei Alexandru a.k.a Sho10
#define ll long long
#define double long double
#pragma GCC optimize("O3")
#pragma GCC optimize("Ofast")
#define all(a) (a).begin(), (a).end()
#define f first
#define s second
#define pb push_back
#define mp make_pair
#define pi pair
#define rc(s) return cout<<s,0
#define endl '\n'
#define mod (10*10*10*10*10*10*10*10*10+7)
#define PI 3.14159265359
#define MAXN 100005
#define INF 1000000005
#define LINF 1000000000000000005ll
#define CODE_START ios_base::sync_with_stdio(false);cin.tie(0);cout.tie(0);
using namespace std;
ll n,m,c[100005];
pair<ll,ll>a[100005];
int32_t main(){
CODE_START;
cin>>n>>m;
for(ll i=1;i<=n;i++)
{
cin>>a[i].s>>a[i].f;
}
for(ll i=1;i<=m;i++)
{
cin>>c[i];
}
sort(c+1,c+m+1);
sort(a+1,a+n+1);
ll l=n,r=m,ans=0;
while(l&&r){
if(a[l].s<=c[r]){
ans++;
r--;
}
l--;
}
cout<<ans<<endl;
}
